Canto IV is the final, unfinished Canto of the Lay of Leithian. It begins with Beren and Lúthien fleeing with the Silmaril through slumbering Angband. But at the gate Carcharoth awoke from the enchantment. He leaped at them before Lúthien could weave another spell, and Beren stood before his beloved, and with his left hand he caught the wolf's throat and with the right he thrust the Silmaril into the eyes of the wolf. The fangs of Carcahroth "crashed together like a trap" and took off Beren's hand, Silmaril and all. There the Lay ends.